Commercial nuclear power generation plants in use as well as those thus far submitted for licensing approval in the United States and abroad are characterized by the following common features with respect of their power generation cycle (e.g. Rankine cycle). First, the motive steam produced which is used to drive the steam turbine is produced at a moderately high pressure with little or no superheat. Second, multiple trains of feedwater heaters are deployed to extract cycle steam at various points and pressures as the steam expands through the turbines (typically high pressure and low pressure turbine units) to pre-heat the condensate (i.e. condenses secondary coolant) before it is returned to the boiler (which may be the reactor itself or a tubular heat exchanger commonly known as the steam generator). Finally, in addition to the string of feedwater heaters, the cycle steam is also generally mechanically dewatered and reheated by the boiler steam (without mixing) in one or two stages in a rather large piece of equipment known as the moisture separator reheater or MSR.
The array of steam turbines, feedwater heaters, MSR, and associated piping, valves and instrumentation, typical of modern nuclear plants, are also a known source of reduction in the plant's reliability and increase in maintenance costs. Although the foregoing equipment mentioned may add perhaps one to two percent to the plant's thermodynamic efficiency, the concomitant increase in complexity, capital cost, and detriment to the plant's availability may be quite significant. In particular, the complexity of the power cycle detracts from the use of the nuclear plant as a variable power supply source for cyclical “load following” operation.